Composition for the production of radily hardening aminosilane cross-linking silicone masses

ABSTRACT

A kit for the production of rapidly-hardening aminosilane cross-linking silicone masses including: 
     (A) 100 parts by weight of an at least bifunctionally terminated diorganopolysiloxane, which include a linear or branched chain of repeating units of the formula ##STR1##  and which contains at least two end groups Z, wherein Z is --H, --OH, OR l  or --SiR 3  (NR 4  R 5 ) 2 , and R l  and R 2  are independently a saturated or unsaturated hydrocarbon radical, optionally substituted with halogen or cyano groups, 
     (B) 0.1 to 20 parts by weight of an aminosilane cross-linker of the general formula 
     
         R.sup.3.sub.y --Si--(NR.sup.4 R.sup.5).sub.4-y 
    
      wherein y=0 or 1, 
     R 3  is hydrogen or a monovalent saturated or unsaturated hydrocarbon or hydrocarbonoxy radical, and 
     R 4  and R 5  are independently selected from hydrogen and saturated or unsaturated aliphatic, cycloaliphatic, or aromatic hydrocarbon radical with 1 to 15 carbon atoms, optionally substituted with halogen or cyano groups, 
     (C) 0.1 to 20 parts by weight of an inorganic or organic compound capable of reacting with an amine to give salt formation 
     (D) 0 to 20 parts by weight of water.

The present invention concerns a kit for the production of rapidlyhardening, aminosilane cross-linking silicone masses consisting of atleast bi-functionally terminated diorganopolysiloxanes, aminosilanecross-linking agents, as well as possibly filling materials, suitableadditives, pigments, colouring materials, oxidation-, heat- andlight-protecting pigments, as well as solvents and plasticisers, as wellas the use as adhesives or moulding materials.

Such organopolysiloxane mixtures, also known as cold-vulcanising, singlecomponent silicone rubbers, usually cross-link at room temperature withthe take-up of water from the surrounding atmosphere to giverubber-elastic polymers. As chain lengtheners and cross-linkers, thereare used bi- and higher functional aminosilane compounds which, byreaction with the polysiloxsne or by hydrolysis, split off amines and soinitiate the formation of a macromolecular meshwork. After hardening hastaken place, such masses are characterised by a good inherent adhesionon the most varied work material surfaces and by a generally highstability against the action of temperature, light, moisture, as well aschemicals.

The hardening of such single-component polysiloxane mixturescross-linking at room temperature with the take-up of moisture takesplace comparatively slowly since the water necessary for the reactionmust diffuse into the interior of the mass in gaseous form from thesurrounding atmosphere. Therefore, the speed of the hardening decreaseswith progressing reaction in the interior of the mass. In the case oflow atmospheric humidity or in the case of an unfavourable ratio ofsurface to volume of the silicone mass, the reaction can become veryslow or, as in moisture-tight closed spaces, can also come to a stop.

The per se diverse possibilities of use of such atmosphericmoisture-hardening silicones as sealing or adhesive material areespecially limited in the case of use for industrial purposes because ofthe slow hardening. Admittedly, two-component silicone rubber systemshardening rapidly at room temperature or hardening first at a highertemperature are known but the use thereof fails frequently because ofthe deficient inherent adhesion or also of the comparatively lowtemperature stability of these products. If, however, one uses siliconeshardening only slowly under the influence of atmospheric moisture, inthe case of short cycle times desired for economic reasons, largeintermediate storages are necessary for the sealed-off or stuck parts inorder to ensure the hardening. These intermediate storages must, inaddition, possibly be climatised or moistened. Under certaincircumstances, in this way, very large numbers of pieces are alreadyproduced before a testing for freedon from fault and function of thegoods produced is first possible. Large-surface adhesions betweendiffusion-tight surfaces can, in practice, be carried out withatmospheric moisture-hardening silicones, such as the production ofmoulded bodies in closed moulds.

If one adds water in liquid form to the known aminosilane-containing andatmospheric moisture-hardening masses, in comparison with thecross-linking with atmospheric moisture a certain acceleration of thehardening is achieved. However, this form of the cross-linking does notlead to end products with material properties such as are obtained inthe case of purely atmospheric moisture cross-linking. On the contrary,masses result which, in the long term, remain substantially softer,display poor inherent adhesion and are still swollen for a long timewith the amine resulting as cross-linking cleavage product. The aminesmell, generally found to be extremely unpleasant, is also maintainedcorrespondingly long.

Similar results, thus only small hardening acceleration combined withcomparatively poorer material properties and with long-lasting aminesmell, are obtained when water is added in the form of salts containingwater of crystallisation or also knowingly surface-moistened materials.

Thus, the task forming the basis of the invention consisted in makingavailable sealing and adhesive masses based on aminosilane cross-linkingpolysiloxane mixtures, whereby, within a short time, i.e. within a fewminutes up to several hours, these are to harden. Furthermore, thehardening is to be independent of the surrounding atmospheric moisture,i.e. it is also to take place in moisture-tight closed regions ormoulds. The typical features of the hitherto known vulcanisatesresulting in the case of atmospheric moisture cross-linking, such as forexample inherent adhesion, mechanical properties and stabilities, arethereby to be substantially maintained.

The task forming the basis of the invention is solved by the features ofthe main claim and promoted by those of the subsidiary claims. Suchmixtures are characterised in that they contain at least the followingcomponents;

A) 100 parts by weight of an at least bifunctionally terminateddiorganopolysiloxane, whereby this is built up from a linear or branchedchain of repeating units of the formula ##STR2## and--as illustrated inthe following in the case of a linear chain--is terminated withfunctional end groups Z ##STR3##

There hereby signify:

R¹, R² : Saturated or unsaturated hydrocarbon radicals, possiblysubstituted with halogen or cyano groups

Z: --H, --OH, OR¹ and SiR³ (NR⁴ R⁵)₂

R³ : hydrogen or monovalent saturated or unsaturated hydrocarbon orhydrocarbonoxy radical with 1-15 carbon atoms

R⁴, R⁵ : hydrogen and/or saturated or unsaturated aliphatic,cycloaliphatic or aromatic hydrocarbon radicals with 1 to 15 carbonatoms, possibly substituted with halogen or cyano groups

B) 0.1 to 20 parts by weight of an aminosilane cross-linker of thegeneral formula

    R.sup.3.sub.y --Si--(NR.sup.4 R.sup.5).sub.4-y

whereby y=0 and 1 and R³, R⁴ and R⁵ have the above meaning.

C) 0.1 to 20 parts by weight of an inorganic or organic compoundreacting with amines with salt formation

D) 0 to 20 parts by weight of water.

As example for the radicals R¹ and R² of the component A are to bementioned any desired saturated alkyl radicals, such as methyl, ethyl,n-propyl, iso-propyl, octyl, dodecyl, octadecyl, but also cyclic ones,such as cyclopentyl and cyclohexyl. Furthermore, unsaturated aliphaticand cycloaliphatic radicals, such as vinyl, allyl, cyclopentenyl orcyclohexenyl, and also aromatic ones, such as phenyl or naphthyl, andaliphatic-substituted aryl radicals, such as for example benzyl ortoluyl, can be used. Within a polysiloxane, the radicals R¹ and R² canbe of the same or different construction. It is also possible to mixbranched and unbranched polysiloxanes of the above-describedconstruction and in different chain length. Polysiloxanes terminatedwith hydroxyl groups, so-called α, Ω-dihydroxydiorganopoly-siloxaneswith methyl and phenyl radicals, are preferably used.

The mentioned radicals can also be used in halogen- andcyano-substituted form. Examples herefor are 1,1,1-trifluorotoluyl,β-cyanoethyl or o-, m- or p-chlorophenyl radicals.

The viscosity of the diorganopolysiloxanes preferably lies in the rangeof 6000 to 350000 mPas.

In the component B, there can additionally be used compounds of theformula

    R.sup.3.sub.2 --Si--(NR.sup.4 R.sup.5).sub.2

These serve as chain lengtheners of the polysiloxanes used.

Besides hydrogen, the radical R³ can be of the same construction as theradicals R¹ and R². Simple alkyl radicals, such as methyl or ethyl, arepreferably used.

The radicals R⁴ and R⁵ can have the same construction as the radicalsR¹, R² or R³, whereby one of the two radicals can also consist of shydrogen atom. Organoaminosilanes, which are to be obtained, forexample, from reactions of methyltrichlorosilanes with primary,aliphatic or cycloaliphatic amines, especially with sec.-butylamine orcyclohexylamine, are preferably used.

As components C, there are suitable carboxylic and mineral acids, suchas for example formic, acetic, citric, tartaric, oxalic, hydrochloric,sulphuric, phosphoric acid, and also acidic salts, such as for examplethe hydrogen phosphates and hydrogen sulphates of ammonium, alkali andalkaline earth metals, possibly also in combination. If these materialsare used in a form containing water of crystallisation, in some casesthe addition of component D to the mixture can be omitted. Preferably,therefore, the dihydrate of oxalic acid is, for example, used.

Component D can be added to the mixture not only in liquid form but alsobound as water of crystallisation, for example as sodium sulphatedecahydrate, or enclosed in zeolites and also adsorbed on the surface offilling materials, such as for example calcium carbonate. The additionof component D preferably takes place in combination with component C,bound as water of crystallisation in the dihydrate of oxalic acid.

To the mixtures of components A to D can be added further materials forthe achievement of special properties. To be mentioned here areespecially coloured pigments and soluble dyestuffs, stabilisers againstoxidation and action of heat, dispersers, reaction catalysts,fungicides, adhesives, solvents, flame-protection agents, plasticisers(preferably silicone oils but also based on hydrocarbons), strengtheningfilling materials, such as for example highly dispersed or precipitatedsilicic acids, graphite, carbon black, as well as passive fillingmaterials, such as e.g. calcium carbonate, silicates, quartz meal, glassand carbon fibres, diatomaceous earth, metal powder, metal oxides,synthetic material powder, as well as hollow spheroids of glass orsynthetic materials.

Mixtures of the components A to D are not storage-stable. Therefore, thecomponents C and D necessary for the reaction acceleration are admiredin a suitable form with the mixture of the components A and Bimmediately before use, preferably pasted in silicone oils or polymers.

If the hardening of the mixtures of the components A to D takes place atelevated temperature, an additional acceleration of the cross-linkingreaction is thereby achieved.

The present invention also concerns a process for the production of asealing or adhesive mixture or moulding mass based on at leastbifunctionally terminated diorganopolysiloxanes and aminosilanecross-linkers, which are characterised in that

A) 100 parts by weight of such a diorganopolysiloxane, whereby this isbuilt up from s linear or branched chain of repeating units of theformula ##STR4## and is terminated, corresponding to the followingformula concerning the special case of linear chains ##STR5## withfunctional end groups Z, and whereby R¹, R² : signify saturated orunsaturated hydrocarbon radicals, possibly substituted with halogen orcyano groups

Z: --H, --OH, OR¹ and --SiR³ (NR⁴ R⁵)₂

R³ : hydrogen or monovalent saturated or unsaturated hydrocarbon orhydrocarbonoxy radical

R⁴, R⁵ : hydrogen and/or saturated or unsaturated aliphatic,cycloaliphatic or aromatic hydrocarbon radical with 1 to 15 carbonatoms, possibly substituted with halogen or cyano groups,

are mixed together with

B) 0.1 to 20 parts by weight of an aminosilane cross-linker of thegeneral formula

    R.sup.3.sub.y --Si--(NR.sup.4 R.sup.5).sub.4-y

whereby y=0 and 1 and R³, R⁴ and R⁵ have the above meaning, as well aspossibly coloured pigments or soluble dye-stuffs, stabilisers againstoxidation and action of heat, dispersers, reaction catalysts,fungicides, adhesives, solvents, flame-protection agents, plasticisers(preferably silicone oils but also plasticisers based on hydrocarbons),furthermore active, strengthening filling materials, such as for examplehighly dispersed or precipitated silicic acids, graphite, carbon black,as well as passive filling materials, such as e.g. calcium carbonate,silicates, quartz meal, glass and carbon fibres, diatomaceous earth,metal powder, metal oxides, synthetic material powder, as well as hollowspheroids of glass or synthetic material, and, immediately before use,

C) 0.1 to 20 parts by weight of an inorganic or organic compoundreacting with amines with salt formation and

D) 0 to 20 parts by weight of water are added thereto.

The mixtures according to the invention themselves adhere to substratesof glass, ceramic, wood, concrete, plaster, metals and syntheticmaterials. Therefore, they are advantageously used as adhesive andsealing materials but are also suitable as protective coating forelectrical insulation, as encapsulation masses for electrical andelectronic constructional parts but also as moulding masses for theproduction of impressions or other moulded parts which are usefullyproduced from elastomers.

In the following, the invention is explained in more detail on the basisof examples.

EXAMPLE 1

100 parts by weight of a component I consisting of 100 parts by weightof an α,Ω-dihydroxydimethylpolysiloxane with a viscosity of 20,000mPa.s, 8 parts by weight of anα,Ω-bis-(trimethylsilyl)-dimethyipolysiloxane with a viscosity of 100mPa.s, 13 parts by weight of a highly dispersed silicic acid with aspecific surface area according to BET of about 110 m² /g 51 parts byweight of calcium carbonate filling material, 9 parts by weight oftris-(cyclohexylamino)-methylsilane are homogeneously mixed together atroom temperature with 20 parts by weight of a component II consisting of80 parts by weight of an α,Ω-bis-(trimethylsilyl)-dimethylpolysiloxanewith a viscosity of 1000 mPs.s, 9 parts by weight of a highly dispersedsilicic acid with a specific surface area according to BET of about 100m² /g, 10 parts by weight of an oxalic acid dihydrate with a grainfineness of <10 μm.

With the exclusion of atmospheric moisture, the mixture obtained fromthe components achieves at room temperature within 60 minutes a Shore-Ahardness of 22°, whereas both components alone under these conditionsremain storage-stable pastes.

If, in the above-described component II, one replaces the oxalic aciddihydrate by a 20% aqueous solution of sulphuric, hydrochloric orphosphoric acid, then, after mixing with the component I, the hardeningthrough already takes place within a few minutes.

EXAMPLE 2

100 parts by weight each of a mixture consisting of 100 parts by weightof an α,Ω-dihydroxydimethylpolysiloxane with a viscosity of 80,000 mPa.s41 parts by weight of an α,Ω-bis-(trimethylsilyl)-dimethylpolysiloxanewith a viscosity of 100 mPa.s 6 parts by weight of a highly dispersedsilicic acid with a specific surface area according to BET of about 150m² /g 123 parts by weight of a calcium carbonate filling material, 12parts by weight of tris-(cyclohexylamino)-methylsilane are, forcomparison, mixed at room temperature in one case with 2 parts by weightof finely crystalline oxalic acid dihydrate and in a further one with0.6 parts by weight of water and stored with the exclusion ofatmospheric moisture.

Already after three hours, the mixture with oxalic acid shows a Shore-Ahardness of 13° Shore-A and shows a slight amine smell whereas themixture only containing water, even after 24 hours, shows no measurableShore-A hardness, is very soft and sticky and smells very strongly ofamine.

I claim:
 1. A kit for the production of a rapidly-hardening aminosilanecross-linking silicone mass comprising:(A) 100 parts by weight of an atleast bifunctionally terminated diorganopolysiloxane, which comprises alinear or branched chain of repeating units of the formula ##STR6## andwhich contains at least two end groups Z, wherein Z is independently--H, --OH, OR¹, or --SiR³ (NR⁴ R⁵)₂, andR¹ and R² are independently asaturated or unsaturated hydrocarbon radical, optionally substitutedwith halogen or cyano groups, (B) 0.1 to 20 parts by weight of anaminosilane cross-linker of the formula

    R.sup.3.sub.y --Si--(NR.sup.4 R.sup.5).sub.4-y

wherein y=0 or 1,R³ is hydrogen or a monovalent saturated or unsaturatedhydrocarbon or hydrocarbonoxy radical, and R⁴ and R⁵ are independentlyselected from the group consisting of hydrogen and saturated orunsaturated aliphatic, cycloaliphatic, or aromatic hydrocarbon radicalwith 1 to 15 carbon atoms, optionally substituted with halogen or cyanogroups, (C) 0.1 to 20 parts by weight of an inorganic or organiccompound capable of reacting with an amine to give salt formation (D) 0to 20 parts by weight of water.
 2. A kit according to claim 1, whereincomponent (B) additionally contains one or more compounds of the formula

    R.sup.3.sub.2 --Si--(NR.sup.4 R.sup.5).sub.2

wherein R³, R⁴, and R⁵ are as defined in claim
 1. 3. A kit according toclaim 1, wherein said inorganic or organic compound (C) comprises anorganic or inorganic acid or a salt of an organic or inorganic acid. 4.A kit according to claim 1, wherein component (C) is contained in a formcontaining water of crystallization.
 5. A kit according to claim 1,wherein component (D) is present and is added in liquid form, bound aswater of crystallization, enclosed in zeolites, or adsorbed on thesurface of filling materials.
 6. A kit according to claim 1 furthercomprising in one of components A-D one or more of a colored pigment,soluble dyestuff, stabilizer against oxidation or heat, disperser,reaction catalyst, fungicide, adhesive, solvent, flame protection agent,plasticizer, active strengthening filling material, passive fillingmaterial, hollow spheroids of glass, or a synthetic material.
 7. A kitaccording to claim 1, wherein component (A) comprises anα,Ω-dihydroxydiorganopolysiloxane.
 8. A kit for the production of arapidly-hardening aminosilane cross-linking silicone mass comprising:(I)100 parts by weight of an at least bifunctionally terminateddiorganopolysiloxane, which comprises a linear or branched chain ofrepeating units of the formula ##STR7## and which contains at least twoend groups Z, wherein Z is independently --H, --OH, OR¹, or --SiR³ (NR⁴R⁵)₂, andR¹ and R² are independently a saturated or unsaturatedhydrocarbon radical, optionally substituted with halogen or cyanogroups, in admixture with 0.1 to 20 parts by weight of an aminosilanecross-linker of the formula

    R.sup.3.sub.y --Si--(NR.sup.4 R.sup.5).sub.4-y

wherein y=0 or 1, R³ is hydrogen or a monovalent saturated orunsaturated hydrocarbon or hydrocarbonoxy radical, and R⁴ and R⁵ areindependently selected from the group consisting of hydrogen andsaturated or unsaturated aliphatic, cycloaliphatic, or aromatichydrocarbon radical with 1 to 15 carbon atoms, optionally substitutedwith halogen or cyano groups; and (II) 0.1 to 20 parts by weight of aninorganic or organic compound capable of reacting with an amine to givesalt formation in admixture with 0 to 20 parts by weight of water.
 9. Aprocess for the production of a sealing or adhesive mixture,comprising:mixing the following components (A) and (B) to give a firstpre-mixture, (A) 100 parts by weight of an at least bifunctionallyterminated diorganopolysiloxane, comprising a linear or branched chainof repeating units of the formula ##STR8## and contains at least two endgroups Z, wherein Z is independently --H, --OH, OR¹, or --SiR³ (NR⁴ R⁵)₂;R¹ and R² are independently selected from saturated or unsaturatedhydrocarbon radicals, optionally substituted with halogen or cyanogroups; (B) 0.1 to 20 parts by weight of an aminosilane cross-linker ofthe formula

    R.sup.3.sub.y --Si--(NR.sup.4 R.sup.5).sub.4-y

wherein y=0 or 1;R³ is hydrogen or a monovalent saturated or unsaturatedhydrocarbon or a hydrocarbonoxy radical; R⁴ and R⁵ are independentlyselected from the group consisting of hydrogen and a saturated orunsaturated aliphatic, cycloaliphatic or aromatic hydrocarbon radicalwith 1 to 15 carbon atoms, optionally substituted with halogen or cyanogroups;and mixing the following components C and D to give a secondpre-mixture, (C) 0.1 to 20 parts by weight of an inorganic or organiccompound capable of reacting with an amine to give salt formation; (D) 0to 20 parts by weight of water, and the first and second premixtures arecombined shortly before use to give an effective sealing and adhesivemixture.
 10. The process according to claim 9, wherein to the firstpre-mixture are further admixed one or more compounds of the formula

    R.sup.3.sub.2 --Si--(NR.sup.4 R.sup.5).sub.2

wherein R³, R⁴ and R⁵ are defined as in claim
 9. 11. A process accordingto claim 9 wherein component (C) comprises one or more organic orinorganic acids or acid salts thereof and, component (D) is present andcomprises water of crystallization, hydrated materials, or wateradsorbed on a zeolite or silica gel or filling material surface.
 12. Aprocess according to claim 9 wherein optionally added to component (C)or (D) or both (C) and (D), are one or more colored pigments, solubledyestuffs, stabilizers against oxidation or heat, dispersers, reactioncatalysts, fungicides, adhesives, solvents, flame protection agents,plasticizers, strengthening filling materials, silicone plasticizers, ordiorganopolysiloxane plasticizers.
 13. A process according to claim 9,wherein component (A) comprises an α,Ω-dihydroxydiorganopolysiloxane.14. A method of coating a substrate comprising mixing the components ofthe kit of claim 1 to form a mixture and applying the mixture to thesubstrate.
 15. A method of producing impressions or other molded partscomprising preparing a mixture from the kit of claim
 1. 16. A substratecoated with a mixture of the components of the kit of claim
 1. 17. Amolding mass comprising a mixture of the components of the kit of claim1.